1. Field of the Invention
This invention relates to a recording/reproducing apparatus to which there is provided a disk cassette accommodating a disk, such as an optical disk, opto-magnetic disk or a magnetic disk. More particularly, it relates to such an apparatus wherein, after the disk cassette has been introduced into a predetermined position in the recording/reproducing apparatus, the disk cassette is shifted along its thickness so as to be positioned in and attached to a cassette attachment section or unit within the recording/reproducing apparatus by the positioning pins engaging in the positioning holes provided in the disk cassette.
2. Description of the Prior Art
In a recording/reproducing apparatus, it is well known that, when the disk including an optical-, an opto-magnetic or an optical disk is directly touched by hands or fingers during its attachment to or removal from the apparatus, fingerprints or the like may be deposited on the disk surface to cause errors in recording and/or reproduction. In order to prevent the disk from being touched directly by hands or fingers during handling, while preventing the dust or dirt from becoming affixed to the disk during storage, the disk is attached to the apparatus as it is accommodated in the cassette half so as to be used in this state for recording and/or reproduction. For this reason, the recording/reproducing apparatus employing this type of the disk cassette as the recording medium is provided with positioning means for positioning the disk cassette with respect to the recording/reproducing apparatus.
As such positioning means, it is known to provide one or more positioning holes in the cassette half of the disk cassette with one or more positioning pins in the cassette attachment unit or section to which the disk cassette is removably mounted, wherein the positioning pins are engaged in the positioning holes for determining the position of the disk cassette within the cassette attachment unit or section. For engaging the positioning pins in the positioning holes, the disk cassette is inserted to a predetermined position into the inside of a cassette holder, after which the cassette holder is shifted along the thickness of the disk cassette, as disclosed in U.S. Pat. No. 3,845,502.
In the recording/reproducing apparatus in which the disk cassette is positioned in the above described manner within the cassette attachment unit or section, it is necessary that, when the disk cassette is inserted to the predetermined position within the cassette holder, the positioning holes formed in the cassette half be positioned substantially coaxially with the positioning pins provided to the cassette attachment unit or section, and be maintained at such position.
To this end, some locking means are provided in the above type of the recording/reproducing apparatus for locking the disk cassette when the disk cassette is inserted to a predetermined position within the cassette holder.
FIG. 1 shows one such conventional locking means.
The locking means shown in FIG. 1 is applied to an optical disk player. A disk cassette 201 applied to the optical disk player is comprised of a rectangular cassette half 202 within which a disk-like optical disk is accommodated. At the corners on the rear side of the cassette half 202 opposite to the side to be introduced into the optical disk player, positioning holes 203, 203 are bored so as to pass through the cassette half 202 along its thickness. On both sides on the front side of the cassette half 202 introduced into the optical disk player, there are formed recesses 204, 204, at the mid portions of which engaging recesses 205, 205 are formed. A shutter 207 is provided to the cassette half 202 for opening or closing an opening 206 confronted by a recording/reproducing pickup, not shown.
Two positioning pins 208, 208 are implanted on a chassis within the optical disk player, and a cassette holder 209 is provided above the chassis. This cassette holder 209 has an inner space within which the disk cassette 201 is accommodated substantially snugly and is adapted to be movable between an eject position for insertion and removal of the optical disk cassette b and a loading end position offset from the eject position towards the interior of the apparatus proper.
On both front sides of the cassette holder 209, a pair of lock levers 210, 210 are supported for being turned horizontally.
When the disk cassette 201 is introduced into the cassette holder 209 to a prescribed inserting position shown by a double-dotted chain line in FIG. 1, the forward ends of the lock levers 210, 210 are resiliently engaged with the engaging recesses 205, 205 formed in the recesses 204, 204 of the cassette half 202. The disk cassette 201 is locked to the cassette holder 209 with a small space margin or allowance. When the cassette holder 209 is shifted from this locked position to the loading end position, the positioning pins 208, 208 are introduced into the positioning holes 203, 203 provided in the cassette half 202 for positioning in the cassette attachment unit or section.
However, the following problems are presented in the locking means for the optical disk player shown in FIG. 1.
The above described locking means are so arranged and constructed that the disk cassette introduced into the cassette holder 209 is locked with the lock levers 210, 210 laterally engaging with the engaging recesses 205, 205 formed on the lateral sides of the disk cassette 201. Thus a space for the lock levers 210, 210 need be provided laterally of the cassette holder 209, with a corresponding increase in the size of the optical disk player in a direction orthogonal to the thickness of the disk cassette 201.
On the other hand, the recording/reproducing apparatus with which the disk cassette is employed is generally standardized in its size and basic structure. With certain standards, it is occasionally not possible to provide the aforementioned space on the lateral sides of the cassette holder within the interior of the recording/reproducing apparatus, in which case the aforementioned locking means can not be installed. Even if the locking means for the cassette holder were installed in the above described manner, the operation of the locking means is necessarily limited because of the spatial constraints.
Also, in the above described locking means, the lock levers 210, 210 are engaged with the engaging recesses 205, 205 formed in the cassette case 202 for locking the disk cassette 201 to the cassette holder 209. These engaging recesses 205, 205 are markedly spaced apart from the positioning holes 203, 203 in the cassette half 202. Thus a considerable shift is caused in the relative disposition between the positioning holes 203, 203 and the positioning pins 208, 208 when the size of the cassette half 202 is changed.
Since the cassette half for this type of the disk cassette is usually formed of synthetic resin, the cassette case size would be markedly changed if the disk cassette or the recording/reproducing apparatus were placed in an environment which is vitally different from that of the ambient temperature, so that considerable changes would be caused in the distance between the engaging recesses 205, 205 of the recesses 204, 204 and the positioning holes 203, 203.
When the disk cassette 201 is locked to the cassette holder 209 with such size shift in the cassette half 202, a shift may be caused in the relative disposition between the positioning holes 203, 203 and the positioning pins 208, 208 since the position of the positioning holes 203, 203 with respect to the cassette holder 209 is shifted considerably from its proper position, although substantially no shifting is caused in the position of the engaging recesses 205, 205 with respect to that of cassette holder 209.
Therefore, in this state, insertion of the positioning pins 208, 208 into the positioning holes 203, 203 cannot be carried out smoothly. Even if such insertion were made successfully, an unduly large force would be applied at the time of such insertion onto the inner surfaces of the positioning holes 203, 203 and the positioning pins 208, 208 in a direction orthogonal to their axial direction. As a result, the cassette half 202 or the positioning pins 208, 208 would be deformed or the movement of the respective parts would be restricted thus giving rise to serious troubles. In case of excess shift, the positioning pins 208, 208 cannot be introduced into the positioning holes 203, 203.
Thus it may be contemplated that suitable locking means be engaged at the rear end face 211 of the cassette half 202 that is closest to the positioning holes 203, 203 for locking the disk cassette 201 introduced into the cassette holder 209. In such case, the locking position of the disk cassette 201 introduced into the cassette holder 109 is so close to the positioning holes 203, 203 that the positioning holes 203, 203 can be controlled to be substantially constant with respect to the cassette holder 209 under the locked condition despite changes in the size of the cassette half 202.
However, such lock means is usually provided between the cassette holder 209 and the cassette inlet provided to the recording/reproducing apparatus. The result is that the length of the recording/reproducing apparatus is increased by a space reserved for the locking means with increased difficulties in the insertion and removal of the disk cassette.
Meanwhile, the cassette half of the disk cassette is usually provided with holes or cut-outs for various purposes, such as finger guides for assisting the insertion and removal of the disk cassette into and out of the recording/reproducing apparatus, or as engagement means for the disk cassette in the automatic disk cassette supply device, these engagement means being occasionally provided in closer proximity to the aforementioned positioning holes.